1. Field of the Invention
This invention relates to a portable circular saw.
2. Description of the Related Art
When a portable circular saw is cutting a workpiece, there occur chips flying. Generally, as viewed in a cutting direction, a front portion of a saw blade is a source of generating chips. It is known to provide a cover for a front portion of a saw blade to prevent an operator (a user) from being exposed to flying chips.
At least a portion of a typical saw-blade cover is made of a transparent member. The transparent cover portion enables an operator to observe a saw blade and an upper surface of a workpiece. Chips deposited on the inner surface of the transparent cover portion hinder the operator""s observation. When chips collide against the transparent cover portion, scars tend to be caused on the inner surface of the transparent cover portion. Also, the scars hinder the operator""s observation.
As will be explained later, a prior-art portable circular saw is poor in ability to prevent an operator from being exposed to flying chips, and in ability to enable chips to smoothly flow in a saw-blade cover.
It is a first object of this invention to provide a portable circular saw which is good in ability to prevent an operator (a user) from being exposed to flying chips.
It is a second object of this invention to provide a portable circular saw which is good in ability to enable chips to smoothly flow in a saw-blade cover.
A first aspect of this invention provides a portable circular saw comprising a base; a saw blade having a portion projecting downward from the base; a saw-blade cover concealing at least a part of the saw blade; and a projection provided on the saw-blade cover and protruding in a direction away from the saw blade, wherein the projection has a lower surface extending across a first plane which is parallel to an axis of rotation of the saw blade, and which contains a tangent to an outer circumference of the saw-blade at a point of intersection with a second plane including a lower surface of the base, and wherein chips fly from the point of intersection along a direction in the first plane, and the lower surface of the projection inclines relative to a line perpendicular to the tangent so as to change a path of a portion of flow of the chips toward a forward side as viewed in a cutting direction.
A second aspect of this invention provides a portable circular saw comprising a base; a saw blade having a portion projecting downward from the base; a saw-blade cover concealing at least a part of the saw blade; a movable slide cover provided on the saw-blade cover, and blocking and unblocking an opening between a front lower end of the saw-blade cover and an upper surface of the base in accordance with upward and downward movement thereof; and a projection provided on the slide cover and protruding in a direction away from the saw blade, wherein the projection has a lower surface extending across a first plane which is parallel to an axis of rotation of the saw blade, and which contains a tangent to an outer circumference of the saw-blade at a point of intersection with a second plane including a lower surface of the base, and wherein chips fly from the point of intersection along a direction in the first plane, and the lower surface of the projection inclines relative to a line perpendicular to the tangent so as to change a path of a portion of flow of the chips toward a forward side as viewed in a cutting direction.
A third aspect of this invention is based on the second aspect thereof, and provides a portable circular saw wherein when the slide cover is in its uppermost position, the projection protrudes from a line connecting a cutting point on the saw blade and a side surface portion of the saw-blade cover in a direction away from the saw blade.
A fourth aspect of this invention is based on the second aspect thereof, and provides a portable circular saw wherein the slide cover is transparent.
A fifth aspect of this invention is based on the second aspect thereof, and provides a portable circular saw wherein the projection extends substantially in parallel with a longitudinal direction of the base.
A sixth aspect of this invention is based on the second aspect thereof, and provides a portable circular saw wherein the projection is provided on a lower end of the slide cover.
A seventh aspect of this invention is based on the second aspect thereof, and provides a portable circular saw wherein a plane including a lower surface of the projection extends across the outer circumference of the saw blade.
An eighth aspect of this invention provides a portable circular saw comprising a base; a saw blade having a portion projecting downward from the base; a saw-blade cover concealing at least a part of the saw blade; a movable slide cover provided on the saw-blade cover, and blocking and unblocking an opening between a front lower end of the saw-blade cover and an upper surface of the base in accordance with upward and downward movement thereof; and a projection provided on and extending inside the slide cover, the projection protruding toward the saw blade.
A ninth aspect of this invention is based on the eighth aspect thereof, and provides a portable circular saw wherein a plane including a lower surface of the projection meets an outer circumference of the saw blade.
A tenth aspect of this invention is based on the eighth aspect thereof, and provides a portable circular saw wherein the slide cover assumes its uppermost position when the projection contacts a lower end of the saw-blade cover.
An eleventh aspect of this invention provides a portable circular saw comprising a saw blade; a saw-blade cover concealing at least a part of the saw blade; a movable slide cover provided on the saw-blade cover; and a flange-like outer projection provided on the slide cover to prevent chips from flying upward out of the slide cover.
A twelfth aspect of this invention provides a portable circular saw comprising a saw blade; a saw-blade cover concealing at least a part of the saw blade; a movable slide cover provided on the saw-blade cover; and a flange-like inner projection provided on the slide cover to reduce an effective cross-sectional area of a path for a flow of chips in the saw-blade cover.